In the industrial world, any commercially distributed item must meet prevailing standards. This is the case especially for food items to which stringent health standards apply. In the agro-food sector, these standards especially lay down maximum permissible quantities of microorganisms such as bacteria in a given volume of product. To verify the presence of these microorganisms and determine their quantity, it is common practice to take samples of foodstuffs and study the progress of microorganisms in a medium that greatly favors their proliferation.
To this end, samples of specific masses are removed from batches of products in order to produce samples that are then placed in Petri dishes. The Petri dish preliminarily contains a solution called agar that fosters the proliferation of this microorganisms when said dish is placed for a certain duration in a chamber regulated at a temperature and a pressure that are very precise. The dishes are opened at different points in time, typically over several days, and are subjected to tests to measure the density of the microorganisms present in the dish and its progress over time. If the density is below a certain threshold, then the batch from which the sample is extracted is considered to be fit for consumption.
The production of agar must be done in a sterile environment to obtain non-polluted samples. The production is done in temperature-regulated and pressure-re-regulated autoclaves. The chamber of the autoclave has a vessel provided with a dual sheathing that communicates cold or heat to the solution contained within it. However, this sheathing takes up a large portion in height of the vessel so that, if the quantity of the content is small and if this content is concentrated at the bottom of the vessel, then the coil heats/cools the walls unnecessarily, causing a lack of homogeneity of temperature.
To limit this problem, present-day autoclaves have a stirrer driven by a motor equipped with a magnetic system situated beneath the vessel. This stirrer is generally constituted by metal blades equipped with magnets in rotation about a shaft fixed to the bottom of the vessel. This layout causes an increase in the height of the apparatus to allow space for the mechanism for driving the stirrer beneath the vessel. In addition, mechanical and magnetic links situated beneath the vessel do not allow the bottom of the vessel to be heated or cooled by means of a heater element and a cooling device. Nor do they allow for a sample to be taken from the center of the culture medium through a tube. Cleaning is a delicate step because it is important to make the vessel perfectly clean and sterile before starting another production operation.
There is therefore a real need for a solution preparator, the vessel of which is easy to clean with a cloth to wipe the interior and a cleaning liquid that can be easily removed.
The present invention proposes a novel model of culture medium preparator that possesses a vessel having fewer uneven surfaces within it while at the same time being provided with a stirrer and an efficient sterilizing device.